Over the recent years, imaging apparatuses such as a video camera, a digital still camera, a broadcasting camera, which employ solid-state imaging device, and a film camera using a silver halide film, have hitherto been enhanced in their functions and downsized on the whole of the apparatus. Then, a zoom lens, which is short in the total lens length and has high resolution, has been required of an imaging optical system for use in such an imaging apparatus (refer to, e.g., Japanese Patent Application Laid-Open No. 2006-284753).
The conventional zoom lens has, however, a problem of not having a sufficient level of optical performance.